1. Field of the Invention
The present invention relates to a wireless communication system, a fixed station device and a mobile station device, and more particularly, applied to a digital cordless telephone system.
2. Description of the Related Art
This type of digital cordless telephone system is comprised of a portable unit which is a cordless telephone and a base unit which is wireless-connected to the portable telephone and is wire-connected to the general telephone network via a wire connection line.
In the digital cordless telephone system, in a state where the base unit is wire-connected to a calling party via the telephone network, the user having the portable unit can talk with the calling party.
In recent years, in such digital cordless telephone system, the portable unit is connected, for example, to a personal computer (hereinafter, referred to as a PC) and this system has been used in the data communications between the PC and a PC of the party of data communications (hereinafter, referred to as a communicating party) which is wire-connected via the telephone network. Thus, the digital cordless telephone system has not been used only as a telephone but the range of its applications has been expanding.
In practice, as shown in FIG. 4, in a portable unit 1 of the digital cordless telephone system, when making a call (i.e., when making a call to the prescribed calling party from the portable unit 1), the user inputs call information by operating an operation key section 2 comprised of call keys and dial keys and thereby, first call information data D1 in digital form is sent from the operation key section 2 to a control unit 4 via a man machine interface 3. In this connection, the call information data D1 to be outputted from the operation key section 2 is also sent to a liquid crystal display (LCD) 5 via the man machine interface 3, and the LCD 5 displays call information shown by the inputted first call information data D1 (i.e., telephone number of the calling party).
In this case, the control unit 4, upon converting the data inputted from the man machine interface 3 into the data having a predetermined data format according to the data transmission by compression and the like (hereinafter, referred to as the format for transmission), transmits the data to a high frequency unit 6 and more over, converts the data inputted from the high frequency unit 6 into the data having the same data format as the data to be inputted from the man machine interface (hereinafter, referred to as the format for I/F) 3 by demodulation and the like. Thus, the control unit 4 converts the first call information data D1 inputted from the man machine interface 3 into the second call information data D2 having the format for transmission to output the data to the high frequency unit 6.
The high frequency unit 6 modulates the data inputted from the control unit 4 based on the control of the control unit 4 with a predetermined format to transmit the resultant transmission data to the base unit (not shown) via an antenna (hereinafter referred to as a portable unit side antenna) and moreover, receives the transmission data transmitted from the base unit via the portable unit side antenna, and demodulates the received transmission data based on the control of the control unit 4 with the predetermined format to modulate to the data having the aforementioned format for transmission. Thus, the high frequency unit 6 modulates the second call information data D2 inputted from the control unit 4 and transmits the resultant transmission data (hereinafter, referred to as call transmission data) D3 to the base unit via the portable unit side antenna.
At this point, when the base unit receives the call transmission data D3 and is wire-connected to the calling party via the telephone network based on the received call transmission data D3, the portable unit 1 receives the user's voice by a microphone 8.
The microphone 8, after converting an audio signal (hereinafter, referred to as a user audio signal) S1 which is analog corresponding to the inputted user's voice into voice data (hereinafter, referred to as first user voice data) D4 formed of digital data via an analog-to-digital converter (hereinafter, referred to as A/D converter) 9, transmits the voice data D4 to the control unit 4 via the man machine interface 3.
The control unit 4 converts the inputted first user voice data D4 into the voice data (hereinafter, referred to as second user voice data) D5 having the format for transmission to transmits this to the high frequency unit 6.
The high frequency unit 6 modulates the inputted second user voice data D5 to transmit the resultant transmission data (hereinafter, referred to as voice transmission data) D6 to the base unit via the portable unit side antenna 7. Moreover, the high frequency unit 6, upon receiving transmission data (hereinafter, referred to as the other party side transmission data) D7 corresponding to the voice data of the calling party (hereinafter, referred to as other party side voice data) transmitted from the base unit via the portable unit side antenna 7, demodulates the data D7 and transmits the resultant other party side voice data (hereinafter, referred to as first other party side voice data) D8 to the control unit 4.
The control unit 4 converts the inputted first other party side voice data D8 into other party side voice data D9 formed of the format for I/F (hereinafter, referred to as second other party side voice data) to transmit to the digital-to-analog converter (hereinafter, referred to as D/A converter) 10 via the man machine interface 3. The D/A converter 10 converts the second other party side voice data D9 into an audio signal (hereinafter, referred to as an other party side audio signal) S2 which is analog to transmit to a speaker 11. With this arrangement, in the portable unit 1, voice of the calling party is uttered from the speaker 11. Thus, the user can talk with the calling party with the portable unit 1.
Furthermore, when a call arrives (i.e., when receiving a call from the calling party), the portable unit 1 receives transmission data (hereinafter, referred to as ringer transmission data) D10 which is transmitted from the base unit and corresponds to ringer data to be obtained from the calling party by the high frequency unit 6, and the high frequency unit 6 demodulates the received ringer transmission data D10 to transmit the resultant first ringer data D11 to the control unit 4.
The control unit 4 converts the inputted first ringer data D11 into second ringer data D12 having the format for transmission to transmit the second ringer data D12 to a ringer 12 via the man machine interface 3. Thereby, the ringer 12 produces a ringer sound such as bell depending on the inputted second ringer data D12. Accordingly, the user knows the arrival of telephone call according to the ringer sound produced by the ringer 12, and then the user operates, for example, the call keys of the operation key section 2 to wire-connect the portable unit 1 to the calling party. Thus, the user and the calling party can communicate in the same way as the case of making a call described above.
Here, in the case of using the portable unit 1 for the data communications, a PC 15 is connected to an earphone jack 13 which is provided in the portable unit 1 via a modem unit 14.
In this case, in a state where the base unit is wire-connected to the communicating party of the data communications in the same way as the case of making a call or receiving a call described above, the PC 15 transmits digital data to be communicated D13 (hereinafter, referred to as first digital data) which is inputted by operating a keyboard or the like provided to the PC 15 by the user, to the modem unit 14.
The modem unit 14, forming a first modulated wave signal S3 showing the inputted first digital data D13 by phase-modulating a predetermined carrier wave according to the first digital data D13, outputs the signal S3 to the A/D converter 9. The A/D converter 9 converts the signal S3 into first modulated wave data D14 formed of digital data and then transmits the data D14 to the control unit 4 via the man machine interface 3.
The control unit 4 converts the inputted first modulated wave data D14 into the second modulated wave data D15 formed of the format for transmission to transmit to the high frequency unit 6, and the high frequency unit 6 modulates the inputted second modulated wave data D15 to transmit the resultant transmission data (hereinafter, referred to as first modulated wave transmission data) D16 to the base unit via the portable unit side antenna 7.
Furthermore, in the portable unit 1, in the case where the data is transmitted to the PC 15 from the communicating party, the high frequency unit 6 receives the transmission data (hereinafter, referred to as second modulated wave transmission data) D17 which is transmitted from the base unit and corresponds to the modulated wave data to be obtained from the communicating party, via the portable unit side antenna 7 to demodulate the transmission data D17, and transmits the resultant modulated wave data (hereinafter, referred to as third modulated wave data) D18 to the control unit 4.
The control unit 4 converts the inputted third modulated wave data D18 into modulated wave data D19 formed of the format for transmission (hereinafter, referred to as fourth modulated wave data) to transmit to the D/A converter 10 via the man machine interface 3. The D/A converter 10 converts the fourth modulated wave data D19 into a modulated wave signal (hereinafter, referred to as a second modulated wave signal) S4 to transmit to the modem unit 14.
The modem unit 14 detects the phase displacement point of the inputted second modulated wave signal S4 and demodulates the second modulated wave signal S4 based on the detected phase displacement point, and transmits the resultant digital data (hereinafter, referred to as second digital data) D20 to the PC 15. Then, based on the inputted second digital data D20, the PC 15 displays the content of the second digital data D20 on the display unit provided to the PC 15, so that the user can visually confirm the content of data communications.
In this connection, a battery 16 is provided in the portable unit 1 which works depending on the electric power to be obtained from the battery 16.
The battery 16 is charged by a battery (not shown) provided outside of the portable unit 1 via a battery control unit 17.
In this case, the battery control unit 17 can charge the battery 16 protecting it from over-charge and moreover, sends the remaining capacity of the battery 16 as battery information data D21 to the LCD 5 via the man machine interface 3 and makes the LCD 5 to display information of the battery 16 shown by the battery information data D21.
Moreover, as shown in FIG. 5, in the base unit 20 of the digital cordless telephone system, when the portable unit 1 makes a call, the call transmission data D3 transmitted from the portable unit 1 is received by a high frequency unit 22 via an antenna (hereinafter, referred to as a base unit side antenna) 21.
In this case, the high frequency unit 22 demodulates the transmission data received via the base unit side antenna 21 with a prescribed format based on the control of the control unit 23 to convert the transmission data into data formed of the format for transmission in the similar way to the high frequency unit 6 of the portable unit 1 described above and transmits the data to the control unit 23 and moreover, modulates the data to be inpu tted from the control unit 23 by the control of the control unit 23 with a prescribed format to convert the data into transmission data. Thus, the high frequency unit 22 demodulates the call transmission data D3 received via the base unit side antenna 21 and transmits the resultant second call information data D2 to the control unit 23.
The control unit 23 converts the data formed of the format for transmission inputted from the high frequency unit 22 into the data formed of the I/F format in the similar way to the control unit 4 of the portable unit 1 described above and then converts the data into an analog signal through the D/A converter provided inside to transmit this to the telephone network through the circuit control unit 24 and wire connection line 25 successively and moreover, digitizes the analog signal to be inputted from the circuit control unit 24 via the A/D converter provided inside and converts the digitized data into data formed of the format for transmission to transmit to the high frequency unit 22. Therefore, the control unit 23 firstly converts the call information data D2 inputted from the high frequency unit 22 into the first call information data formed of the I/F format, and then converts the first call information data into the call information signal S6 which is analog via the D/A converter, and transmits the signal S6 to the telephone network via the circuit control unit 24 and the wire connection line 25 successively. Thus, in the telephone network, the base unit 20 and the calling party will be wire-connected based on the inputted call information signal S6.
At this point, in a state where the base unit 20 is wire-connected to the calling party via the telephone network, the voice transmission data D6 transmitted from the portable unit 1 is received by the high frequency unit 22 via the base unit side antenna 21.
The high frequency unit 22 demodulates the received voice transmission data D6 and transmits the resultant second user voice data D5 to the control unit 23. The control unit 23 converts the inputted second user voice data D5 into the first user voice data, and then converts the data into the user audio signal S1 to transmit to the telephone network via the circuit control unit 24 and the wire connection line 25 in order.
Furthermore, the base unit 20 supplies the other party side audio signal S2 to be obtained from the calling party via the telephone network to the control unit 23 via the wire connection line 25 and the circuit control unit 24 in order.
The control unit 23, after converting the inputted other party side audio signal S2 into the digitized first other party side voice data via the D/A converter, converts the data into the first other party side voice data D8 formed of the format for transmission to transmit to the high frequency unit 22.
The high frequency unit 22 modulates the inputted first other party side audio signal S2 to transmit the resultant other party side transmission data D7 to the portable unit 1 via the base unit side antenna 21. In this way, the base unit 20 enables the user having the portable unit 1 and the calling party to talk to each other.
Furthermore, in the base unit 20, when a call arrives in the portable unit 1, the ringer signal S7 which is analog to be obtained from the calling party via the telephone circuit network is inputted to the control unit 23 via the wire connection line 25 and the circuit control unit 24 in order, and the control unit 23 converts the inputted ringer signal S7 into the first ringer data D11 to transmit to the high frequency unit 22.
The high frequency unit 22 modulates the inputted first ringer data D11 and transmits the resultant ringer reception data D10 to the portable unit 1 via the base unit side antenna 21. In this way, when the portable unit 1 and the calling party are wire-connected, the base unit 20 enables the user and the calling party to talk to each other in the similar way to the case of making a call described above.
Furthermore, in the base unit 20, in the case where the data is transmitted to the communicating party from the PC 15 connected to the portable unit 1, in a state of being wire-connected to the communicating party in the similar way to the case of making a call and receiving a call described above, the high frequency unit 22 receives the first modulated wave transmission data D16 transmitted from the portable unit 1 via the base unit side antenna 21.
The high frequency unit 22 demodulates the received first modulated wave transmission data, and transmits the resultant second modulated wave data D15 to the control unit 23. The control unit 23 converts the inputted second modulated wave data D15 into the first modulated wave signal S3 to transmit to the telephone network via the circuit control unit 24 and the wire connection line 25 in order.
Furthermore, in the base unit 1, when transmitting the data to the PC 15 connected to the portable unit 1 from the communicating party, the second modulated wave signal S4 which is analog to be obtained from the communicating party via the telephone network is inputted to the control unit 23 via the wire connection line 25 and the circuit control unit 24 in order. The control unit 23, after converting the inputted digital second modulated wave signal S4 into third modulated wave data D18 formed of digital data, transmits the data to the high frequency unit 22.
The high frequency unit 22 modulated the inputted third modulated wave data D18 to transmit the resultant second modulated wave transmission data D17 to the portable unit 1 via the base unit side antenna 21. Accordingly, the base unit 20 enables the PC 15 wire-connected to the portable unit 1 and the communicating party to communicate data to each other.
In the digital cordless telephone system constructed as described above, the transmission rate of the wireless zone between the portable unit 1 and the base unit 20 is set to become approximately 28800 (bps) in advance. At this point, in the digital cordless telephone system, if the first modulated wave transmission data D16 (or the second modulated wave transmission data D17) is transmitted in the wireless zone at the transmission rate described above, it is necessary to sample and digitize the first modulated wave signal S3 (or the second modulated wave signal S4) with the comparatively high predetermined sampling frequency corresponding to the transmission rate in the A/D converter 9 of the portable unit 1 (or the A/D converter in the control unit 23 of the base unit 20) and the first modulated wave signal S3 (or the second modulated wave signal S4) may be sampled at the timing more than the cycle of its phase displacement point.
However, in the case of converting the digitized first modulated wave data D15 (or the fourth modulated wave data D19) into analog form again and demodulating at the communicating party side (or the portable unit 1), it was difficult to detect the phase displacement point of the analog first modulated wave signal S3 (or the second modulated wave signal S4) and it was difficult to demodulate the first modulated wave signal S3 (or the second modulated wave signal S4).
Furthermore, in the control unit 23 (or the circuit control unit 24) of the base unit 20 (or the portable unit 1), in the case of compressing and demodulating the second modulated wave data D15 (or the third modulated wave data D16), it was difficult to detect the phase displacement point.
In addition to these problems, in the digital cordless telephone system, by digitizing the first modulated wave signal S3 at the portable unit 1 and converting the digitized first modulated wave data D15 into analog form at the base unit 20, the first modulated wave signal S3 obtained by the portable unit 1 is converted into digital data and analog signal repeatedly, so that noise may occur in the first modulated wave data D15 and the first modulated wave signal S3 every modulation and it has a problem in that the phase displacement point of the first modulated wave signal S3 is difficult to be detected.
Accordingly, in the digital cordless telephone system, the first modulated wave data D16 (or the second modulated wave data D17) could be transmitted in the wireless zone between the portable unit 1 and the base unit 20 at the transmission rate approximately 9600 (bps) at the maximum, thus the data communications was very inefficient.